This invention relates to a control type liquid-in vibration isolating device used to support a power unit of an automobile engine and the like for the purpose of vibration isolation.
A control type liquid-in vibration isolator or isolating device, in which vibration isolating characteristics are obtained according to two kinds of vibration with different frequency range such as shake and idle vibration, has previously been suggested as a liquid-in vibration isolating device used for a mount supporting a vibration generating body such as an automobile engine and the like so as not to transmit its vibration to a vehicle body.
For example, for a conventional liquid-in vibration isolating device, a switching control type liquid-in vibration isolating device comprises a vibration isolating substrate a rubber elastomer, a cylindrical body fitting connected with the vibration isolating substrate, a first diaphragm fitted to the body fitting opposite to the vibration isolating substrate, a partition portion interposed between the vibration isolating substrate and the first diaphragm. A main liquid chamber is formed between the partition portion and the vibration isolating substrate and a first sub-liquid chamber is formed between the partition portion and the first diaphragm to connect through a first orifice with the main liquid chamber. A second sub-liquid chamber connects through the second orifice with the main liquid chamber, and a switching chamber for the atmospheric or negative pressure is formed separated through the second diaphragm from the second sub-liquid chamber.
As this kind of existing double-orifice control type liquid-in vibration isolating device, two orifices which connect the main liquid chamber with the first and second sub-liquid chambers are either serially connected or disposed in parallel, respectively.
Therefore, in order to form another orifice, the cost is increased due to extra processing required, increased number of manhours needed for manufacturing, additional space required for storage, and the larger outside diameter and weight of the device. Besides, if the property is varied due to errors of accuracy and the like of the components, one will not make adjustments easily and also cannot cope with a change in the property easily, with the result that the adjustments will be troublesome.
The present invention has been made in view of the problems described above, and provides the control type liquid-in vibration isolating device capable of easily coping with a variation or change of the property and also providing two orifices compactly.
A liquid-in vibration isolating device of the present invention comprises a vibration isolating substrate a rubber elastomer, a cylindrical body fitting connected with the vibration isolating substrate, a first diaphragm fitted and adhered to the body fitting opposite to the vibration isolating substrate, a partition portion interposed between the vibration isolating substrate and the first diaphragm, a main liquid chamber formed between the partition portion and the vibration isolating substrate, a first sub-liquid chamber formed between the partition portion and the first diaphragm, a second sub-liquid chamber provided with a second diaphragm on the main liquid chamber side of the partition portion, the main liquid chamber and the first and second sub-liquid chambers being connected through the orifice, respectively, and has the following configuration to alleviate the problems described above.
The partition portion comprises a partition main member forming a first orifice connecting the first sub-liquid chamber, a partition plate member forming the second sub-liquid chamber and a second orifice connecting to the sub-liquid chamber in combination with the partition main member on the main liquid chamber side, and these members are fitted to the body fitting. The first and second orifices share an inlet/outlet on the main liquid chamber side, and the first orifice is diverged from a part of a path of the second orifice having a smaller liquid passing resistance than that of the first orifice. As idle vibration, the second orifice has a sectional area, that is, a path cross-sectional area larger than the first orifice for the shake vibration.
According to the liquid-in type vibration isolating device, since the first orifice connecting the main liquid chamber and the first sub-liquid chamber is diverged from a part of the path of the second orifice having a small liquid passing resistance connecting the main liquid chamber and the second sub-liquid chamber, two orifices can be configured compactly in spite of double orifice type vibration isolating device. Also, the number of manhours needed for manufacturing is decreased and the cost of manufacturing can also be reduced by sharing a single inlet/outlet of both orifices on the main liquid chamber side.
By sharing a single inlet/outlet of both orifices on the main liquid chamber side as described above, a variation in the property is diminished. Besides, one can easily cope or deal with any variation or change in the property by making a position adjustment when combining with the partition main member and/or the partition plate member which form the first and second orifices.
Furthermore, since the sectional area of the second orifice for the idle vibration is larger than that of the first orifice for the shake vibration, the second orifice exhibits vibration damping function for the idle vibration, and the first orifice for the shake vibration exhibits vibration damping function which is hardly affected by the path from the inlet/outlet to the divergent position of the first orifice.
As for the control liquid-in vibration isolating device, it is desirable that the second diaphragm is disposed inwardly on the main liquid chamber side of the partition main member to form a switching chamber capable of selectively introducing the atmospheric and negative pressure, and that the circumferential edge portion of the second diaphragm is forced or pushed-in by the partition plate member disposed on the main liquid chamber side of the partition main member to form the second sub-liquid chamber between the diaphragm and itself. It is also desireable that a hollow space surrounded between the partition main member and the partition plate member is formed outwardly thereof as the second orifice extending circumferentially.
With the foregoing construction, the function of the first and second orifices can be changed over and controlled easily by introducing the atmospheric and negative pressure into the switching chamber.
The liquid-in type vibration isolating device can be configured by providing the divergent path of the first orifice opening to the second orifice path on the partition main member, opening the inlet/outlet into the main liquid chamber on a part of the partition plate member, and adjusting and combining the circumferential position of the partition plate member as against the partition main member. Consequently, one can make adjustments in the property during assembly or adjustments for a property change easily, thus obtaining stable properties.
The partition main portion can be configured by forming a concave portion for the orifice continuously connected from the divergent path on the first sub-liquid chamber side, forming the first orifice with the concave portion on the first sub-liquid chamber side covered by the partition support plate, and providing an opening at a part of the position corresponding to the concave portion on the partition support plate. Consequently, one can easily produce the partition main member, and also easily adjust the length of the first orifice by adjusting the position of the opening within a range of the length of the concave portion.